Origin

Late 15th century: from Latin, literally 'poor'. The word's use in English originated in the Latin legal phrase in forma pauperis, literally 'in the form of a poor person' (allowing non-payment of costs).

The Latin word for ‘poor’ pauper, is the base of pauper (early 16th century), poverty (Middle English), and poor. The phrase poor as a church mouse, or ‘extremely poor’, comes from the notion that a church mouse must be particularly deprived as it does not have the opportunity to find pickings from a kitchen or larder, and there are few crumbs to be found in a well-swept church. You sometimes hear a wealthy young person whose money appears to bring them no happiness described as poor little rich girl (or boy). Though he did not coin the phrase, Noël Coward certainly popularized it with his 1925 song ‘Poor Little Rich Girl’.